#!/usr/bin/env python
# -*- coding:utf-8 -*-
# @FileName  :CircleArea.py
# @Time      :2020/6/22 9:48
# @Author    :Administrator
import math

r = float(input("请输入圆的半径:"))
area = math.pi * r ** 2
print('半径为{0}的圆面积是:{1}'.format(r, area))
